When manufacturing spiral-toothed bevel gears, the tooth gaps are predominantly machined out from the small to the large diameter of the gear body using a cutter head. A burr arises at the outer tooth end in this case through the machining, predominantly on the concave flank, because this flank typically forms an acute angle with the rear face of the bevel gear tooth. If one merely removed the burr at this point, a very sharp profiled edge would remain. Because of the great danger of injury, but also because of harmful deformations when hardening the bevel gears, these edges are frequently broken by a chamfer. If this angle is not so acute, because the bevel gear has a small spiral angle, for example, it is sufficient to deburr the edge.
Devices which were developed for conventional mechanical bevel gear cutting machines are known for this chamfering and/or deburring of bevel gears. Even during the milling of the bevel gears in the discontinuous dividing method, the tooth ends are deburred after each tooth gap. Or in the continuous method, the chamfering and/or deburring is performed after the gear cutting in a separate work cycle.
Separately standing deburring devices are also frequently used. In these devices, the disadvantage of additional workpiece clamping is accepted in order to have more space available in proximity to the workpiece than in a gear cutting machine, because then the deburring tools may be set more flexibly and easily to the particular workpiece dimensions. In addition, more bevel gears may be cut on a gear cutting machine in the same time if they do not also have to be deburred there.
A deburring device of this type, in which two different milling cutters are used for deburring, each of which has its own rotary drive, is described in DE 197 44 486 A1. The cutters are positioned on a shared support and operate with the bevel gear at a standstill using one single radial feed motion. It is disadvantageous in this case that the milling cutters must be aligned to one another and each milling cutter requires a special profiled shape for its cutting edges, which must be tailored to the particular bevel gear to be deburred.
Another separate chamfering device for bevel gears, which operates using a rotationally driven end-milling cutter, originates from DE 298 01 318 U1. In this case, the cutter spindle is movable in 3 axes, specifically horizontally, vertically, and in a pivot, in relation to the workpiece carrier, which is controllable around its axis, and a controller is provided for coupling the four axial motions, through which the end-milling cutter is guided along a programmed path. In addition to the disadvantages which are connected with a separate deburring device, in this device, in spite of the great mechanical engineering complexity, the outer tooth ends of slender shaft pinions cannot be chamfered.
In a known deburring device which is used directly on a gear cutting machine, a multipass fly-milling cutter is used, whose axis of rotation is set so that the cutting edge of the fly cutter moves along the profiled edge of a bevel gear tooth to be chamfered. This device operates not in the indexing method, but rather with constant workpiece rotation, so that each following fly cutter engages in the next bevel gear gap in sequence. The decisive disadvantage, however, is that not all bevel gears may be deburred on their gear cutting machine using a fly-milling cutter. A further disadvantage is that special fly-milling cutters must be used. In addition, space for a fly-milling cutter must be provided in the machine.
A gear cutting machine, in which a tool referred to as a planing tool, which is attached to a pneumatically-operated piston, is used, is described in German Published Application 11 85 039 A. An essential disadvantage of this known device is that the planing tool may machine each tooth end with a cut whose direction may be set, but is then linear per se. The profiled edge to be deburred is a spatially strongly curved curve, however, which results from the intersection of two faces, specifically the bevel gear flank having adjoining foot rounding, which is curved anyway, and the rear face of the bevel gear tooth. The latter is typically a bevel face which may be additionally set back and/or rounded at the tooth end once again. This means that the profiled edge may not be chamfered correctly using the known device. At most an averaging direction may be set, and the device must then plane away a significant quantity of material in order to deburr the complete tooth height. Secondary burrs may form easily in this case, which is just as undesirable. In addition, it is hardly possible to avoid a sharp notch arising in the foot rounding, due to the shaping tool, which impairs the load capacity of the bevel pinion. A further disadvantage is the complexity with which a linear shaping device must be set manually to the particular workpiece dimensions.
Similar disadvantages also related to the deburring device operating in one axis according to the Japanese publication JP 10-180542 A, which is also used in a gear cutting machine. In this case, the shaping tool comprises an angle lever, which is mounted so it is rotatable at its vertex. Its short leg is implemented to form a straight cutting edge, while a pneumatically-operated piston again engages on the longer leg. The holder for the angle lever and the piston must be aligned precisely as in the device according to DE 11 85 039 A, so that the cutting edge, which is guided on a circular arc, moves in an averaging direction along the profiled edge of the stationary bevel gear. This device is also not usable for deburring bevel gears and particularly bevel pinions. In addition, it is a disadvantage that a special shaping tool is necessary.
Therefore, the present invention is based on the object of designing a bevel gear cutting machine in such a way that, using little complex apparatus, greatly varying types of bevel gears may be chamfered and/or deburred, as well as providing a corresponding method.
A further object of the present invention is to design a bevel gear cutting machine in such a way that the longer dwell time of the workpiece in the gear cutting machine caused by the deburring is relatively short.